The dual notch worked on Apple, as it didn’t use the index hole either. Woz didn’t see any sense in the index hole. This scheme only worked after the media for all the disks were two sided, oxide on both sides of the mylar. At first they were made from the same sheets as 1/2” magnetic tape, which has oxide on only one side.
My first floppy drive was in 1978 and it sure beat paper tape!
Brantley Coile
> On Jul 2, 2016, at 12:37 AM, SZIGETI Szabolcs <szigiszabolcs at gmail.com> wrote:
>> Hi,
>> I think that only worked on the Commodore 64 and likes, where the drive did not use the index hole to identify the start of sectors/tracks. Punching a hole there was much harder operation, than cutting a new write protect notch.
>> Szanolcs
>> 2016.07.02. 2:16 ezt írta ("Dave Horsfall" <dave at horsfall.org>):
> On Fri, 1 Jul 2016, Marc Rochkind wrote:
>> > Those original floppies were I believe 160K. If you paid extra, the box
> > would hold two drives. Later, IBM introduced double-sided drives, at
> > 320K each.
>> Those in the know, of course, simply put a notch on the opposite side.
>> --
> Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."